Thank you, Charles, for the reference. Much as I had been looking for a concise, practical answer, I realize that I know little to nothing about the chemistry at play here (my background is in micro-electronics), and so a little education is definitely in order.

Turns out Powell's Books here in Portland had a nice, affordable copy on the shelf, just waiting for me. Now I just have to find an excuse to go downtown and pick it up...

Originally Posted by CMB

Add to this: non-toxic, no dark reaction, and capable of long term storage after sensitization.

I always thought the last 2 were intrinsic to this family of compounds. I guess not.

While you've previously identified the UltraStable sensitizer, I'd also like to find compounds that may be more readily available, and perhaps less expensive ($54 for 10 grams from the one source I was able to find online) than that, though I certainly don't know how far 10g would take me.